// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.

#![allow(non_snake_case)]

use core::num::{NonZeroU32, NonZeroUsize};
use regorus::languages::rego::compiler::Compiler;
use regorus::rvm::program::{
    generate_assembly_listing, generate_tabular_assembly_listing, AssemblyListingConfig,
    DeserializationResult, Program as RvmProgram,
};
use regorus::rvm::vm::{ExecutionMode, RegoVM};
use regorus::{compile_policy_with_entrypoint, PolicyModule, Rc, Value};
use serde::Deserialize;
use std::sync::Arc;
use wasm_bindgen::prelude::*;

#[wasm_bindgen]
/// WASM wrapper for [`regorus::Engine`]
pub struct Engine {
    engine: regorus::Engine,
}

#[derive(Deserialize)]
struct ModuleSpec {
    id: String,
    content: String,
}

#[derive(Deserialize)]
#[serde(rename_all = "camelCase")]
struct PolicyLengthSpec {
    max_col: u32,
    max_file_bytes: usize,
    max_lines: usize,
}

#[cfg(feature = "cache")]
#[derive(Deserialize)]
struct CacheConfigSpec {
    regex: usize,
    glob: usize,
}

/// Configure the global pattern caches used by regex and glob builtins.
///
/// Accepts a JS object: `{ regex, glob }`.
#[cfg(feature = "cache")]
#[wasm_bindgen(js_name = "setCacheConfig")]
pub fn set_cache_config(config: JsValue) -> Result<(), JsValue> {
    let spec: CacheConfigSpec = serde_wasm_bindgen::from_value(config).map_err(error_to_jsvalue)?;
    regorus::cache::configure(regorus::cache::Config {
        regex: spec.regex,
        glob: spec.glob,
    });
    Ok(())
}

/// Clear all entries from every pattern cache.
#[cfg(feature = "cache")]
#[wasm_bindgen(js_name = "clearCache")]
pub fn clear_cache() {
    regorus::cache::clear();
}

#[wasm_bindgen]
pub struct Program {
    program: Arc<RvmProgram>,
}

#[wasm_bindgen]
pub struct ProgramDeserializationResult {
    program: Arc<RvmProgram>,
    is_partial: bool,
}

#[wasm_bindgen]
impl ProgramDeserializationResult {
    /// Whether the program was partially deserialized.
    #[wasm_bindgen(getter)]
    pub fn isPartial(&self) -> bool {
        self.is_partial
    }

    /// Get the deserialized program.
    pub fn program(&self) -> Program {
        Program {
            program: self.program.clone(),
        }
    }
}

#[wasm_bindgen]
pub struct Rvm {
    vm: RegoVM,
}

fn error_to_jsvalue<E: std::fmt::Display>(e: E) -> JsValue {
    JsValue::from_str(&format!("{e}"))
}

impl Default for Engine {
    fn default() -> Self {
        Self::new()
    }
}

impl Clone for Engine {
    /// Clone a [`Engine`]
    ///
    /// To avoid having to parse same policy again, the engine can be cloned
    /// after policies and data have been added.
    fn clone(&self) -> Self {
        Self {
            engine: self.engine.clone(),
        }
    }
}

#[wasm_bindgen]
impl Engine {
    #[wasm_bindgen(constructor)]
    /// Construct a new Engine
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html
    pub fn new() -> Self {
        Self {
            engine: regorus::Engine::new(),
        }
    }

    /// Turn on rego v0.
    ///
    /// Regorus defaults to rego v1.
    ///
    /// * `enable`: Whether to enable or disable rego v0.
    pub fn setRegoV0(&mut self, enable: bool) {
        self.engine.set_rego_v0(enable)
    }

    /// Add a policy
    ///
    /// The policy is parsed into AST.
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.add_policy
    ///
    /// * `path`: A filename to be associated with the policy.
    /// * `rego`: Rego policy.
    pub fn addPolicy(&mut self, path: String, rego: String) -> Result<String, JsValue> {
        self.engine.add_policy(path, rego).map_err(error_to_jsvalue)
    }

    /// Add policy data.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.add_data
    /// * `data`: JSON encoded value to be used as policy data.
    pub fn addDataJson(&mut self, data: String) -> Result<(), JsValue> {
        let data = regorus::Value::from_json_str(&data).map_err(error_to_jsvalue)?;
        self.engine.add_data(data).map_err(error_to_jsvalue)
    }

    /// Get the list of packages defined by loaded policies.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.get_packages
    pub fn getPackages(&self) -> Result<Vec<String>, JsValue> {
        self.engine.get_packages().map_err(error_to_jsvalue)
    }

    /// Get the list of policies.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.get_policies
    pub fn getPolicies(&self) -> Result<String, JsValue> {
        self.engine.get_policies_as_json().map_err(error_to_jsvalue)
    }

    /// Clear policy data.
    ///
    /// See https://docs.rs/regorus/0.1.0-alpha.2/regorus/struct.Engine.html#method.clear_data
    pub fn clearData(&mut self) -> Result<(), JsValue> {
        self.engine.clear_data();
        Ok(())
    }

    /// Set input.
    ///
    /// See https://docs.rs/regorus/0.1.0-alpha.2/regorus/struct.Engine.html#method.set_input
    /// * `input`: JSON encoded value to be used as input to query.
    pub fn setInputJson(&mut self, input: String) -> Result<(), JsValue> {
        let input = regorus::Value::from_json_str(&input).map_err(error_to_jsvalue)?;
        self.engine.set_input(input);
        Ok(())
    }

    /// Evaluate query.
    ///
    /// See https://docs.rs/regorus/0.1.0-alpha.2/regorus/struct.Engine.html#method.eval_query
    /// * `query`: Rego expression to be evaluate.
    pub fn evalQuery(&mut self, query: String) -> Result<String, JsValue> {
        let results = self
            .engine
            .eval_query(query, false)
            .map_err(error_to_jsvalue)?;
        serde_json::to_string_pretty(&results).map_err(error_to_jsvalue)
    }

    /// Evaluate rule(s) at given path.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.eval_rule
    ///
    /// * `path`: The full path to the rule(s).
    pub fn evalRule(&mut self, path: String) -> Result<String, JsValue> {
        let v = self.engine.eval_rule(path).map_err(error_to_jsvalue)?;
        v.to_json_str().map_err(error_to_jsvalue)
    }

    /// Gather output from print statements instead of emiting to stderr.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.set_gather_prints
    /// * `b`: Whether to enable gathering prints or not.
    pub fn setGatherPrints(&mut self, b: bool) {
        self.engine.set_gather_prints(b)
    }

    /// Set the policy length limits used when loading policies.
    ///
    /// Accepts a JS object: `{ maxCol, maxFileBytes, maxLines }`.
    pub fn setPolicyLengthConfig(&mut self, config: JsValue) -> Result<(), JsValue> {
        let spec: PolicyLengthSpec =
            serde_wasm_bindgen::from_value(config).map_err(error_to_jsvalue)?;
        self.engine
            .set_policy_length_config(regorus::PolicyLengthConfig {
                max_col: NonZeroU32::new(spec.max_col)
                    .ok_or_else(|| JsValue::from_str("maxCol must be non-zero"))?,
                max_file_bytes: NonZeroUsize::new(spec.max_file_bytes)
                    .ok_or_else(|| JsValue::from_str("maxFileBytes must be non-zero"))?,
                max_lines: NonZeroUsize::new(spec.max_lines)
                    .ok_or_else(|| JsValue::from_str("maxLines must be non-zero"))?,
            });
        Ok(())
    }

    /// Clear the policy length configuration, reverting to defaults.
    pub fn clearPolicyLengthConfig(&mut self) {
        self.engine.clear_policy_length_config();
    }

    /// Take the gathered output of print statements.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.take_prints
    pub fn takePrints(&mut self) -> Result<Vec<String>, JsValue> {
        self.engine.take_prints().map_err(error_to_jsvalue)
    }

    /// Enable/disable policy coverage.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.set_enable_coverage
    /// * `b`: Whether to enable gathering coverage or not.
    #[cfg(feature = "coverage")]
    pub fn setEnableCoverage(&mut self, enable: bool) {
        self.engine.set_enable_coverage(enable)
    }

    /// Get the coverage report as json.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.get_coverage_report
    #[cfg(feature = "coverage")]
    pub fn getCoverageReport(&self) -> Result<String, JsValue> {
        let report = self
            .engine
            .get_coverage_report()
            .map_err(error_to_jsvalue)?;
        serde_json::to_string_pretty(&report).map_err(error_to_jsvalue)
    }

    /// Clear gathered coverage data.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.clear_coverage_data
    #[cfg(feature = "coverage")]
    pub fn clearCoverageData(&mut self) {
        self.engine.clear_coverage_data()
    }

    /// Get ANSI color coded coverage report.
    ///
    /// See https://docs.rs/regorus/latest/regorus/coverage/struct.Report.html#method.to_string_pretty
    #[cfg(feature = "coverage")]
    pub fn getCoverageReportPretty(&self) -> Result<String, JsValue> {
        let report = self
            .engine
            .get_coverage_report()
            .map_err(error_to_jsvalue)?;
        report.to_string_pretty().map_err(error_to_jsvalue)
    }

    /// Get AST of policies.
    ///
    /// See https://docs.rs/regorus/latest/regorus/struct.Engine.html#method.get_ast_as_json
    #[cfg(feature = "ast")]
    pub fn getAstAsJson(&self) -> Result<String, JsValue> {
        self.engine.get_ast_as_json().map_err(error_to_jsvalue)
    }
}

#[wasm_bindgen]
impl Program {
    /// Compile an RVM program from modules and entry points.
    pub fn compileFromModules(
        data_json: String,
        modules_json: String,
        entry_points_json: String,
    ) -> Result<Program, JsValue> {
        let data = Value::from_json_str(&data_json).map_err(error_to_jsvalue)?;
        let modules: Vec<ModuleSpec> =
            serde_json::from_str(&modules_json).map_err(error_to_jsvalue)?;
        let entry_points: Vec<String> =
            serde_json::from_str(&entry_points_json).map_err(error_to_jsvalue)?;
        if entry_points.is_empty() {
            return Err(error_to_jsvalue(
                "entry_points must contain at least one entry",
            ));
        }

        let policy_modules: Vec<PolicyModule> = modules
            .into_iter()
            .map(|module| PolicyModule {
                id: Rc::from(module.id.as_str()),
                content: Rc::from(module.content.as_str()),
            })
            .collect();

        let entry_points_ref: Vec<&str> = entry_points.iter().map(|s| s.as_str()).collect();
        let compiled =
            compile_policy_with_entrypoint(data, &policy_modules, Rc::from(entry_points_ref[0]))
                .map_err(error_to_jsvalue)?;
        let program = Compiler::compile_from_policy(&compiled, &entry_points_ref)
            .map_err(error_to_jsvalue)?;
        Ok(Program { program })
    }

    /// Serialize a program to binary format.
    pub fn serializeBinary(&self) -> Result<Vec<u8>, JsValue> {
        self.program
            .serialize_binary()
            .map_err(|e| error_to_jsvalue(e.to_string()))
    }

    /// Deserialize an RVM program from binary format.
    pub fn deserializeBinary(data: Vec<u8>) -> Result<ProgramDeserializationResult, JsValue> {
        let (program, is_partial) =
            match RvmProgram::deserialize_binary(&data).map_err(error_to_jsvalue)? {
                DeserializationResult::Complete(program) => (program, false),
                DeserializationResult::Partial(program) => (program, true),
            };
        Ok(ProgramDeserializationResult {
            program: Arc::new(program),
            is_partial,
        })
    }

    /// Generate a readable assembly listing.
    pub fn generateListing(&self) -> Result<String, JsValue> {
        Ok(generate_assembly_listing(
            self.program.as_ref(),
            &AssemblyListingConfig::default(),
        ))
    }

    /// Generate a tabular assembly listing.
    pub fn generateTabularListing(&self) -> Result<String, JsValue> {
        Ok(generate_tabular_assembly_listing(
            self.program.as_ref(),
            &AssemblyListingConfig::default(),
        ))
    }
}

#[wasm_bindgen]
impl Rvm {
    #[wasm_bindgen(constructor)]
    pub fn new() -> Self {
        Self { vm: RegoVM::new() }
    }

    /// Load a program into the VM.
    pub fn loadProgram(&mut self, program: &Program) {
        self.vm.load_program(program.program.clone());
    }

    /// Set VM data from JSON.
    pub fn setDataJson(&mut self, data_json: String) -> Result<(), JsValue> {
        let data = Value::from_json_str(&data_json).map_err(error_to_jsvalue)?;
        self.vm.set_data(data).map_err(error_to_jsvalue)
    }

    /// Set VM input from JSON.
    pub fn setInputJson(&mut self, input_json: String) -> Result<(), JsValue> {
        let input = Value::from_json_str(&input_json).map_err(error_to_jsvalue)?;
        self.vm.set_input(input);
        Ok(())
    }

    /// Set execution mode (0 = run-to-completion, 1 = suspendable).
    pub fn setExecutionMode(&mut self, mode: u8) -> Result<(), JsValue> {
        let mode = match mode {
            0 => ExecutionMode::RunToCompletion,
            1 => ExecutionMode::Suspendable,
            _ => return Err(error_to_jsvalue("invalid execution mode")),
        };
        self.vm.set_execution_mode(mode);
        Ok(())
    }

    /// Execute the program and return the JSON result.
    pub fn execute(&mut self) -> Result<String, JsValue> {
        let value = self.vm.execute().map_err(error_to_jsvalue)?;
        value.to_json_str().map_err(error_to_jsvalue)
    }

    /// Execute an entry point by name and return the JSON result.
    pub fn executeEntryPoint(&mut self, entry_point: String) -> Result<String, JsValue> {
        let value = self
            .vm
            .execute_entry_point_by_name(&entry_point)
            .map_err(error_to_jsvalue)?;
        value.to_json_str().map_err(error_to_jsvalue)
    }

    /// Resume execution with an optional JSON value.
    pub fn resume(&mut self, resume_json: Option<String>) -> Result<String, JsValue> {
        let value = if let Some(json) = resume_json {
            Some(Value::from_json_str(&json).map_err(error_to_jsvalue)?)
        } else {
            None
        };
        let result = self.vm.resume(value).map_err(error_to_jsvalue)?;
        result.to_json_str().map_err(error_to_jsvalue)
    }

    /// Get the execution state as a string.
    pub fn getExecutionState(&self) -> String {
        format!("{:?}", self.vm.execution_state())
    }
}

impl Default for Rvm {
    fn default() -> Self {
        Self::new()
    }
}

#[cfg(test)]
mod tests {
    use crate::error_to_jsvalue;
    use wasm_bindgen::prelude::*;
    use wasm_bindgen_test::wasm_bindgen_test;

    #[wasm_bindgen_test]
    #[allow(dead_code)]
    pub fn basic() -> Result<(), JsValue> {
        let mut engine = crate::Engine::new();
        engine.setEnableCoverage(true);

        // Exercise all APIs.
        engine.addDataJson(
            r#"
        {
           "foo" : "bar"
        }
        "#
            .to_string(),
        )?;

        engine.setInputJson(
            r#"
        {
           "message" : "Hello"
        }
        "#
            .to_string(),
        )?;

        let pkg = engine.addPolicy(
            "hello.rego".to_string(),
            r#"
            package test
            message = input.message"#
                .to_string(),
        )?;
        assert_eq!(pkg, "data.test");

        let results = engine.evalQuery("data".to_string())?;
        let r = regorus::Value::from_json_str(&results).map_err(error_to_jsvalue)?;

        let v = &r["result"][0]["expressions"][0]["value"];

        // Ensure that input and policy were evaluated.
        assert_eq!(v["test"]["message"], regorus::Value::from("Hello"));

        // Test that data was set.
        assert_eq!(v["foo"], regorus::Value::from("bar"));

        // Use eval_rule to perform same query.
        let v = engine.evalRule("data.test.message".to_owned())?;
        let v = regorus::Value::from_json_str(&v).map_err(error_to_jsvalue)?;

        // Ensure that input and policy were evaluated.
        assert_eq!(v, regorus::Value::from("Hello"));

        let pkgs = engine.getPackages()?;
        assert_eq!(pkgs, vec!["data.test"]);

        engine.setGatherPrints(true);
        let _ = engine.evalQuery("print(\"Hello\")".to_owned());
        let prints = engine.takePrints()?;
        assert_eq!(prints, vec!["<query.rego>:1: Hello"]);

        // Test clone.
        let mut engine1 = engine.clone();

        // Test code coverage.
        let report = engine1.getCoverageReport()?;
        let r = regorus::Value::from_json_str(&report).map_err(error_to_jsvalue)?;

        assert_eq!(
            r["files"][0]["covered"]
                .as_array()
                .map_err(crate::error_to_jsvalue)?,
            &vec![regorus::Value::from(3)]
        );

        println!("{}", engine1.getCoverageReportPretty()?);

        engine1.clearCoverageData();

        let policies = engine1.getPolicies()?;
        let v = regorus::Value::from_json_str(&policies).map_err(error_to_jsvalue)?;
        assert_eq!(
            v[0]["path"].as_string().map_err(error_to_jsvalue)?.as_ref(),
            "hello.rego"
        );
        Ok(())
    }
}